海底地震仪与拖揽观测系统的联合走时层析海水速度建模  

Joint traveltime tomography for seawater based on ocean bottom seismometer and towed streamer observations

作　　者：刘雯 刘玉柱[1,2] 王建花 张建明 伍正 杨涛 LIU Wen;LIU YuZhu;WANG JianHua;ZHANG JianMing;WU Zheng;YANG Tao(School of Ocean and Earth Science,Tongji University,Shanghai 200092,China;State Key Laboratory of Marine Geology,Tongji University,Shanghai 200092,China;CNOOC Research Institute Co.,Ltd.,Beijing 100028,China)

机构地区：[1]同济大学海洋与地球科学学院,上海200092 [2]同济大学海洋地质国家重点实验室,上海200092 [3]中海油研究总院,北京100028

出　　处：《地球物理学报》2024年第6期2378-2387,共10页Chinese Journal of Geophysics

基　　金：国家自然科学基金(41930105);中国海洋石油有限公司"十四五"重大科技课题(KJGG-2022-0104)资助。

摘　　要：在海洋地震勘探过程中,如果不考虑海水的非均匀性将会在后续层析成像过程中引入伪影,因此准确的海水速度建模是非常有必要的.海底地震仪(OBS)记录数据中的透射波具有较大的射线角度,能够为海水建模提供垂向分辨率;而拖缆观测可以补充OBS分布稀疏造成的横向欠采样,同时可以定位海底深度并更新OBS位置信息.综合利用OBS和拖缆观测系统可以克服各自的局限性,提高海水速度建模的精度.为此,本文提出了一种基于OBS与拖缆观测系统的海水透射波、海底反射波联合走时层析方法,同时反演海水声速分布和海底深度.二维理论模型实验和实际资料处理结果表明,该方法能够准确反演海水声速分布和海底深度,提高震相走时的匹配程度,为后续成像提供准确的非均匀海水模型.In marine seismic exploration,overlooking the heterogeneity of seawater can introduce artifacts in subsequent tomography or imaging process.Therefore,it is crucial to establish precise seawater velocity model.The data captured by ocean bottom seismometers(OBSs)records transmitted waves with substantial ray angles,offering valuable vertical resolution for seawater velocity modeling.Towed streamer observations can complement the under-sampling issues resulting from the sparse distribution of OBSs.Additionally,they help determine seafloor depth,which,in turn,can be used to update OBS positions.The combined utilization of OBS and towed streamer observations allows us to overcome the limitations of each method and significantly enhances the accuracy of seawater velocity modeling.This paper proposed a joint tomographic method based on OBS and towed streamer observations.It leverages the traveltimes of seawater-transmitted waves and seabed-reflected waves to inverse the distribution of seawater sound velocity and seabed depth while concurrently updating OBS depths.The validity of this method is confirmed through both two-dimensional theoretical models and field data experiments.The results unequivocally demonstrate that this proposed approach accurately determines seawater sound velocity distribution and seabed depth,consequently improving the alignment of traveltimes with seismic phases and providing a precise model of heterogeneous seawater velocity for subsequent imaging.

关 键 词：海底地震仪 海水速度建模 走时层析 海水透射波 海底反射波 

分 类 号：P631[天文地球—地质矿产勘探] P718[天文地球—地质学]